Folding and degradation of membrane proteins

膜蛋白的折叠和降解

• 批准号: 10580673
• 负责人: Heedeok Hong
• 金额: $ 30.97万
• 依托单位: MICHIGAN STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-03-01 至 2027-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10580673
• 关键词: ATP-Dependent Proteases; Affect; Biological Models; Cell membrane; Cells; Chemicals; Disease; Engineering; Environment; Escherichia coli; Eukaryotic Cell; Goals; In Vitro; Inherited; Knowledge; Learning; Lipid Bilayers; Mediating; Membrane; Membrane Proteins; Methodology; Methods; Modeling; Molecular; Molecular Chaperones; Monitor; Mutation; Outcome Study; Peptide Hydrolases; Physiological; Prokaryotic Cells; Property; Proteins; Proteome; Quality Control; Research; Signal Pathway; Solvents; Stress Response Signaling; System; Vision; Water; design; human disease; innovation; misfolded protein; novel; physical property; programs; protein degradation; protein folding; protein misfolding; protein protein interaction; public health relevance; stem; thermophilic organism; thermostability

ABSTRACT (Project Title: Folding and Degradation of Membrane Proteins) The goal of my research program is to elucidate the chemical and physical principles underlying the folding and degradation of membrane proteins. Cells should maintain physiologically optimal levels of functional proteins. This is achieved by the balanced actions of molecular chaperones to facilitate folding, proteases to degrade misfolded and superfluous proteins, and stress-response signaling pathways to regulate levels of chaperones and proteases. This protein quality control machinery uses multiple layers of mechanisms to monitor the folding status of a proteome. Thus, the fate of a given protein, whether it will fold or be degraded, strongly depends on the intrinsic folding properties of the protein. While a majority of folding and degradation studies have focused on water-soluble proteins, it is not well understood how the intrinsic folding properties of membrane proteins affect their degradation. The knowledge gap mainly stems from inherent difficulties in studying membrane protein folding in their native lipid bilayer environment as well as an insufficient understanding of folding and sequence determinants for degradation. We use a combined model employing the membrane-integrated ATP-dependent protease FtsH of E. coli as a model degradation machine, and the intramembrane protease GlpG of E. coli as a model substrate, both of which are widely conserved in prokaryotic and eukaryotic cells. We developed an array of methods to study membrane protein folding in the bilayers based on the novel steric-trapping principle. We also developed an in vitro bilayer system to study FtsH-mediated degradation of a membrane protein. Using these methodological innovations, my vision for future research is to learn the generalizable lessons of folding, protein-protein interactions and quality control of membrane proteins in the cell membranes. We will delve into three unanswered problems: 1) What is the detailed molecular mechanisms of FtsH-mediated membrane protein degradation? 2) Is the lipid bilayer a good solvent for the denatured states of membrane protein or a poor solvent that promotes their nonspecific collapse? 3) How do membrane proteins from thermophilic organisms achieve their unusual thermostability and activity? If successful, the outcome of this study will advance our fundamental understanding of mechanisms and energetics of membrane protein degradation, identify new physical properties of the lipid bilayer that control folding and interactions of membrane proteins, and discover new stabilizing motifs for membrane proteins that will provide a useful design and engineering principle.

抽象的 （项目名称：膜蛋白的折叠和降解） 我的研究计划的目标是阐明潜在的化学和物理原理 膜蛋白的折叠和降解。细胞应该 维持生理最佳水平 的功能性蛋白质。这是通过分子伴侣的平衡作用来实现的，以促进 折叠、蛋白酶降解错误折叠和多余的蛋白质以及应激反应信号 调节伴侣和蛋白酶水平的途径。这种蛋白质质量控​​制机器 使用多层机制来监测蛋白质组的折叠状态。于是，一个人的命运 给定的蛋白质，无论它会折叠还是被降解，很大程度上取决于内在的折叠特性 的蛋白质。虽然大多数折叠和降解研究都集中在水溶性 蛋白质，目前尚不清楚膜蛋白的内在折叠特性如何影响 他们的退化。知识差距主要源于研究膜的固有困难 蛋白质在其天然脂质双层环境中的折叠以及对 降解的折叠和序列决定因素。我们使用组合模型 大肠杆菌的膜整合 ATP 依赖性蛋白酶 FtsH 作为模型降解机， 以及大肠杆菌的膜内蛋白酶 GlpG 作为模型底物，两者均被广泛应用 在原核和真核细胞中保守。我们开发了一系列的研究方法 基于新颖的空间捕获原理的双层膜蛋白折叠。我们也 开发了一种体外双层系统来研究 FtsH 介导的膜蛋白降解。 利用这些方法创新，我对未来研究的愿景是学习可推广的知识 细胞内膜蛋白折叠、蛋白质-蛋白质相互作用和质量控制的课程 膜。我们将深入研究三个悬而未决的问题：1）详细的分子结构是什么？ FtsH介导的膜蛋白降解机制？ 2）脂双层是良溶剂吗 用于膜蛋白的变性状态或促进其非特异性的不良溶剂 坍塌？ 3) 嗜热生物的膜蛋白如何实现其不寻常的作用 热稳定性和活性？如果成功的话，这项研究的结果将推动我们的基础研究 了解膜蛋白降解的机制和能量学，识别新的 控制膜蛋白折叠和相互作用的脂质双层的物理特性， 并发现新的膜蛋白稳定基序，这将提供有用的设计和 工程原理。